The state-wide Iowa case-control study of orofacial clefts is nearing our initial goal of 300 case and 300 control families. Participants have completed telephone interviews and mailed questionnaires. Blood samples for DNA preparation have been obtained by mailing blood collection kits to local clinicians. Preliminary analyses reveal an association between maternal smoking during pregnancy and increased risk of isolated clefts that is strongly modified by social class; poorly educated women appear highly susceptible to the effects of smoking. Maternal alcohol drinking was also associated with isolated clefts. The TGFA gene has been previously linked to isolated clefts. We found an association between TGFA TaqI and K primer alleles and increased susceptibility to the cleft- inducing effects of maternal alcohol drinking; the sample size was small however and the results were not statistically significant, but this warrants further study. TGFA polymorphisms also appeared to increase the susceptibility to clefting in mothers with no or irregular use of multivitamins during pregnancy. Our present sample size precludes accurate assessment of gene-environment interactions because the candidate genes are rare. We therefore propose to expand the sample size by simplifying data collection and expanding it to other states. Case and control subjects born during 1992-1997 will be ascertained by the birth defect registries in Iowa, Arizona, Arkansas, Hawaii, and Oklahoma. A mailed questionnaire will focus on strong "candidate" environmental causes including maternal smoking, alcohol use, and diet. DNA from mailed buccal swabs will be analyzed by PCR by Dr. Murray in Project 2. A sample of 1000 cases of isolated clefts and 1000 controls will yield sufficient statistical power (greater than or equal to 0.80 at alpha=0.05) to detect odds ratios (ORs) of 1.5 or greater given exposures of 30 percent among controls and ORs of 3.0 or greater at exposure rates of 3%. Pilot projects include development of procedures for the retrieval of newborn screening blood spots from the centralized laboratories in each state and testing the study procedures in more diverse populations including Asians and Pacific Islanders in Hawaii, Native Americans in Arizona and Oklahoma, and African-Americans and Hispanics in each state.